During next decade, automotive engineers will take up unprecedented challenges to technical demands on passenger cars. Reducing the impact on the environment not only in urban areas but also on the global basis will become an increasingly urgent issue. In addition, the need for energy saving will necessitate development of more fuel efficient cars, and exploitation of alternative energy. This paper analyzes on the tasks assigned to future automotive engines, and discusses on those problems awaiting solutions by the dawn of the coming century.

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An experimental study of the laminar-turbulent transition of the rotating low pressure wall boundary layer has been conducted. Emphasis was placed upon the probability of generation and growth rate of the turbulent spot and their relationship to the intermittency factor. Emmons model was modified to take into account the spacial distribution of the origin of the spot, and was compared with the Dhawan-Narasimha model. Its applicability to the rotating boundary layer was discussed.

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Visual expressions are examined for the enfire transition process of nonexcited and acoustically excited jets. A multi-smoke-wire method with diluted oil gave clear pictures of the streamwise transition of coherent vorticities in the jets. Four types of velocity vector maps are obtained by the conditional sampling method. The velocity vector fields analysed by the double decomposition were favorable with respect to behavior of the coherent vortices and meandering motion of the jets. The triple decomposition analysis requires that keen attention be paid to the interpretation of results, though it can show the nature of the coherent structure from a different viewpoint.

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Two-dimensional numerical simulations of Taylor vortex flows considering acceleration rates of the inner cylinder were conducted to clarify the generating mechanisms of the primary, the secondary normal and the anomalous modes. We found that higher acceleration rates produce such strong vorticity for the cells on the end walls that a larger number of cells are induced toward the center. Slower increasing rates of the Re number promote diffusion of vorticity into the center of the cylinder. The modes are determined by the balance between induction and diffusion of the vorticity. The end cells degenerate in anomalous modes with certain acceleration rates. These weakened small cells are called "extra" or "hidden" vortices. We show that the extra vortices are end vortices which have become unstable and dissipate.

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The successive over-relaxation (SOR) method is often adopted for incompressible viscous flow analyses. Since the efficiency of the SOR method is much affected by the relaxation parameter ω, it has been thought that we should use the optimum relaxation parameter, ω_opt, to minimize CPU time. A numerical experiment was conducted in the present study to examine whether ω_opt is the best strategy for transient flow analyses. This examination clarified that ω_opt is not always the best strategy. This is because the efficiency of the SOR method is determined not only by the relaxation parameter but also by the relation between an initial error and a convergence criterion. Then, an ω-controller was proposed. This controller determines the value of ω by making use of ω_opt, the initial error and the convergence criteria. It was confirmed by numerical experiments that the proposed controller is effective for reducing the CPU time of transient flow analyses.

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Numerical calculations of steady flows of polymeric liquid crystals between parallel plates have been carried out using the molecular theory derived by Doi. Some simplifications including a decoupling approximation are employed in order to avoid calculation difficulties. The velocity profiles are flat in comparison with Newtonian flow because of the shear-thinning viscosity possessed by the liquid crystalline polymers. On approaching the channel wall, the order parameters increase and the preferred angles of molecules measured with respect to the flow direction decrease. The position of the centerline is singular for the preferred angle. The mean-field potential has the effect of strongly orienting the rod molecules. Therefore, the increase of the potential is responsible for the drop in the viscosity and for the decrease of the preferred angle.

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In this paper, the pseudo-shock wave produced in the process of the interaction of the reflected shock wave with the contact surface in a shock tube were investigated numerically in order to crarify the mechanism of its production. The computations were carried out by solving the two dimensional and compressible Navier-Stokes equations by means of TVD method. The calculations were performed for the various strengths of the shock waves, and the flow fields were expressed by means of the contour lines of the presure and the density, velocity vectors, pressure distributions and the distance-time diagrams of the shock waves. The numerical results showed clearly the process of the production and the development of the pseudo-shock wave, and the effects of the strength of the reflected shock wave and Reynolds number of the flow were clarified.

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Experiments on the falling velocity of a sphere in the acceleration range were performed with dilute polymer solutions and exhibited drag reduction. Six spheres were tested. Spheres between 7.93mm and 14.95mm in diameter were dropped into an acrylic resin vessel, 1010mm high by 300mm in diameter, filled with dilute polymer solution. The equation for the motions of a sphere in Newtonian fluids were analyzed numerically, and the results were compared with the experimental data. The results obtained in this study showed that the onset points of drag reduction on the drag of a sphere can be estimated using a parameter associated with the falling velocity and the sphere diameter.

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A method for measurement of temperature in rarefied gas flow has been developed. The flow field is visualized by planar laser-induced fluorescence (PLIF) of iodine molecules seeded in carrier gas. Iodine molecules have many absorption lines in the visible region and radiate intense fluorescence. The fluorescence intensity is proportional to the number of molecules in the energy level excited by the laser beam. From the dependence of this number on the temperature, the local temperature can be decided from the ratio of the fluorescence intensities of two visualized images which are obtained by irradiations of laser beams with different wavelengths. This method allows to image the two-dimensional temperature distribution of the flow field by means of a laser sheet and a high-sensitivity CCD camera. In this paper, the method for selection of optimum combinations of two absorption lines in the transition of B(v'=43)←X(v"=0) is provided theoretically, and this is verified by means of the temperature measurement of the flow field of a supersonic free jet in which temperature varies drastically.

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This paper describes Viscoelastic fluid flow through 2 : 1 planar contraction in the case Where the inertia force is not neglected. Streak photographs are obtained using aqueous solutions of polyacrylamide. A new numerical method to analyze viscoelastic fluid flolws is proposed. This method is derived by applying the CIP (Cubic-Interpolated Pseudo Particle) scheme to the constitutive equation. It is clarified by comparisons with experimental results and numerical simulation that the numerical results by the Maxwell model are in good agreement with the experimental results.

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In order to predict various phenomena related to flow and heat transfer in space, it is necessary to carry out experiments under microgravity. In this paper, we describe the behavior of a horizontal two-phase flow under microgravity utilizing a drop tower 6.1m in height, which realizes microgravity conditions of less than 0.02G(G=g/g₀) for about one second when the capsule is falling down. The experiment was carried out in a horizontal transparent acrylic resin tube of 10mm I. D. and 250mm length, using Freon-22 and water as the working fluid, in a superficial gas velocity range of 0.021m/s to 5.05m/s (Re_G=58∼1.4×10⁴) and a superficial water velocity of 0.022m/s to 0.456m/s (Re_L=246∼5.1×10³). The flow patterns obtained under microgravity were compared with other data under actual microgravity utilizing a drop tower. Furthermore, the base liquid film thickness, the height of waves and the period of waves in the region of annular flow, were obtained from a measured shape of waves. Then, the relationship between these values, gas Reynolds number and liquid film Reynolds number was obtained. Also, the void fraction under microgravity could be expressed using the distribution parameter and the Martinelli parameter.

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The relationship between the growth of inlet reverse flow and the change in separation point in a suction flow was studied experimentally in a helical inducer. The relationship between the decrease in flow rate and the change in pressure distribution on a suction pipe wall was examined in detail at the point where the inlet reverse flow occurs. Furthermore, flow visualization, with the aid of the streakline method, was carried out to observe the occurrence of flow separation in the suction pipe flow. As a result of the present study, it is confirmed that the separation in a suction pipe occurs just upstream of the inlet reverse flow region. It is also known that the adverse pressure gradient appears in the pipe flow in the partial capacity range, which may be considered as a cause of the suction flow separation.

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The effective use of high-frequency oscillation (H. F. O.) requires precise knowledge of the Taylor dispersion of gas on the oscillatory flow. In this study, axial gas transport and turbulent characteristics were measured on the oscillatory flow at and near resonance frequency, in a straight circular pipe to simulate the trachea. The velocity profiles are measured by a hot wire anemometer. The effective dispersion coefficient was determined by the measurement of the carbon dioxide concentration which was dispersed from the injection point. The turbulence appeared at the frequency near the resonance and turbulent intensity and kurtosis achieved maximum values at the beginning of the deceleration phase. Furthermore, the integral scale was enlarged and the lateral mixing of carbon dioxide was enhanced by the large turbulent diffusion coefficient.

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The assessment of turbulence models including a second-moment closure and the standard k-ε model has been performed for calculating a turbulent separated flow over a surface mounted obstacle. The results indicate more complex characteristics in this problem compared to backward facing step flow which is often used as the test case of turbulence models. Although the required computational effort is much higher than that of the k-ε model, the superior performance of the second-moment closure model is evident in representing the velocity field immediately above the obstacle as well as the pressure variation along the channel. It is indicated that the shortcomings of the k-ε model are attributable to the erroneous behaviour of the production rate of turbulent kinetic energy as calculated according to the eddy viscosity assumption.

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This paper deals with an experimental study of the flow in a logarithmic spiral curved diffuser with uniform inlet velocity distribution. In this study, the effects of the variation in the interposed position of the guide vane in a diffuser and the position of its leading edge on the pressure distributions along both diffuser walls, velocity and vector distributions, and the diffuser efficiency are clarified. The results obtained from this study are summarized as follows : In the case where the ratio, b_n/B₁, of the distance b_n between the convex wall and the interposed position of the guide vane at the diffuser inlet to the diffuser inlet breadth B₁ is in the region of about 0.25∼0.375, the diffuser efficiency indicates the most desirable value. When the leading edge of the guide vane is placed upstream, superior diffuser efficiency can be obtained, in every interposed position of a guide vane.

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Radiation contribution to the total heat transfer at the immersed surface in high-temperature fluidized beds has been a controversial subject. Some investigators have reported that it is significant, and others say it is not. The controversy has resulted from the ambiguity of the specification of the temperatures of the beds and heat transferring surfaces. Most experiments were conducted in a combustion fluidized bed with water-cooled tubes immersed in the beds. Radiation effects might not appear when the surface temperatures are low, even if the bed temperatures are high. In this report, a gas-cooled thin tube was immersed in a gas combustion fluidized bed, in order to keep both the bed and tube temperatures high enough to observe the radiation effects. The results show that the radiation contribution to total heat transfer becomes significant as both the tube and bed temperatures increase. The transient temperature profiles and the characteristics of the exhaust gas of the gas combustion fluidized bed are also reported.

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This paper presents the results of experiments on flat-plate helical inducers. In order to offer sufficient data for designing helical inducers, various inducers were fabricated and tested. The number of blades, the blade length and the blade angle were varied systematically, and the overall performance and exit flow condition of each inducer were measured. The results obtained can be summarized as follows. (1) The number of blades and blade length have optimum values. (2) The ratio of axial velocity at outlet to that at inlet is about 1.3, and turning angle and pressure loss depend only on attack angle, in spite of the differences in inducers and flow rate. Consequently, head rise can be easily estimated using these results.

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An implicit time-marching finite-difference method for solving two-dimensional compressible Navier-Stokes equations is applied to the numerical analysis of transonic viscous flows through a steam turbine cascade. The distinctive feature of this method is its use of the momentum equations of contravariant velocity components. A high-order accurate difference scheme modified from the Chakravarthy-Osher TVD scheme is used in order to clearly capture shock waves which occur at the blade trailing edges. Steam-tunnel tests to measure losses of a linear cascade of transonic steam turbine blades are carried out in order to verify the effectiveness of the numerical method. Computed shock wave structures agree well with Schlieren photographs of the cascade tests. The agreement between the computed results and the measurements of total pressure loss coefficients and those of total pressure profiles in the blade wakes is also found to be reasonable.

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A method is presented for the aerodynamic characteristics of the cascade of porous flat plates, which are porous sails with infinitely high tension. In this analysis the authors apply a series of Jacobi's polynomials to express the pressure difference across the membrane. As a result of this numerical analysis, the effects of porosity on the coefficient of interference and the position of the center of pressure are shown in diagrams as functions of solidity and stagger angle. With an increase in the porosity the pressure difference across the membrane increases near the tailing edge, and decreases near the leading edge. As a result, the center of pressure moves back toward the middle point of the chord when the porosity increases.

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The flow characteristics of the turbine stage, which runs at a high pressure ratio, are complicated by the appearance of shock and expansion waves. An exact numerical method by which to calculate the influence of such unsteady phenomena is impossible due to interaction and reflection of shock waves effected by the boundary layer. Therefore, flow visualization of the entire stage cascade on running was made by the Schlieren method employing a stroboscope, and a flow analysis was executed on the basis of the photograph's color. In addition, the pressure fluctuation at the stationary blade exit point was measured. Detached shock waves created in front of the moving blades could verify the influence on the cascade flow.

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Experimental investigations directed towards improving the performance of the impulse turbine with self-pitch-controlled guide vanes are reported. Two types of tandem guide vanes are presented and tested : those with variable-pitch flat-plate and those with variable-pitch splitter. The results show that a high-efficiency impulse turbine can be developed through the use of the splitter. It is found that, in this case, the upstream guide vanes act as a slotted nozzle blade row and the downstream vanes as a tandem diffuser blade row by changing the pitch angle of the splitter automatically in a reciprocating flow. It is also found that the running and starting characteristics of this turbine in the reciprocating flow can be evaluated from the performance of the turbine with fixed nozzle and diffuser vanes in a unidirectional steady flow.

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This paper describes the comparison between the experimental results and the analytical results for the surging limits of a multistage axial-flow compressor with a decompression suction chamber in front of the compressor. The analysis is based on the simplest two-element model for the compressor rotor flow passage, which is connected to the lumped parameter model extended to the decompression chamber. In this paper, it is shown that the surging limits are affected by the compressor discharge volume and the existence of the decompression system.

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Through-vane compressors are used for automotive air conditioners, and they are different from conventional sliding vane compressors in the respect that the vanes run through a rotor and both tips of the vanes are guided by the inner wall of a cylinder. In the through-vane compressor, a friction loss occurs at one tip of the vane contacting the cylinder wall, while a leakage loss occurs at the other tip of the vane. This study investigates the behavior of the vane theoretically by solving balancing equations of force and moment acting on the vane. The theoretical calculation elucidates the magnitude of the contacting force between the vane tip and the cylinder wall and identifies the region of the contact which extends from a suction process to the first half of a compression process of the compressor. Effectiveness of the calculation is confirmed by comparing the theoretical region of the contact with the practical contacting region estimated from flow visualizing experiments.

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In order to clarify the scaling effects on cavitation erosion, erosion pits are carefully measured using a digital image processing technique for four similar flat-hydrofoils with chord length C from 53mm to 160mm, corresponding to the cavitation aspects, under similar conditions of cavitation-nuclei size-distribution in the test water, flow velocity, angle of attack and cavitation number. Because the cavitation intensity is correspond to types of cavitation and it is also associated with cavitation-nuclei size-distribution and flow velocity. The erosion intensity I_ER, that is defined by the diameter of erosion pits and the pitting rate, is determined to be a power law : I_ER ∝ Cⁿ. In the average erosion intensity over the hydrofoils, the exponent n is 2, while at the maximum local erosion intensity, the exponent n is 4.5. The erosion pits predominantly result from the vortex cavitation.

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The paper presents a new defrosting method in which a frost layer is melted away by radiative heat as a heat source. The optical characteristics of the horizontal frost layer (reflectivity, transmissivity, absorptivity) are obtained under various frost melting conditions. The far-infrared lamp having a maximum wavelength of 5.5μm is selected as the optimum radiative heat source for the melting frost. The frost layer melting experiments with radiative heat are carried out under various exvironmental parameters (radiative heat flux, environmental air temperature, air humidity, cooling brine temperature) and frost structural factors of density and porosity. The useful dimensionless equations for predicting the time taken for complete frost melting are derived as a function of various frost melting parameters.

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Numerical analysis has been conducted for combined free and forced laminar convection of liquid metals in a horizontal pipe which is isothermally heated from a certain axial location. The steady-state solutions have been obtained in consideration of axial conduction for Peclet numbers of 0.3∼7.5 and Rayleigh numbers of 15∼500. The results reveal marked effects of axial conduction on the flow and heat transfer characteristics of liquid metals. At the entrance to the heated section, the secondary flow has already developed and a reverse flow occurs near the pipe top as the buoyancy effect becomes large. Consequently, the circumferential average Nusselt number decreases with increasing secondary flow in comparison with that observed in moderate and large Prandtl-number flows. The regime of reverse flow is clearly identified in the Pe-Ra coordinates.

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The mutual diffusion coefficients of CFC11-air and HCFC123-air systems have been measured at 30-180°C and at atmospheric pressure by the Taylor method. The experimental uncertainty was estimated to be ±2%. The present results can be represented by the following equations: CFC11-air, D=3.19×10^-10T^1.80, HCFC123-air, D=4.30×10^-10T^1.74, where D is the mutual diffusion coefficient in m^2/s and T is the temperature in K. The mutual diffusion coefficient of the HCFC123-air system is found to be lower by 4-6% than that for the CFC11-air system.

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This paper deals with a pseudo-continuous model for the prediction of radiative transfer in fibrous media. The proposed model incorporates the fiber orientation and effective fiber length in the determination of the radiative properties of the medium. Applicability of the model in the prediction of radiative properties of fibrous media is justified on the basis of experimental findings. In this study, a planar fibrous medium in which every fiber is oriented parallel to the boundaries stratifying the medium is adopted as a test specimen. The scattered radiation from a single fiber taken out of the medium is first measured to determine the complex refractive index of the fiber material. The experimentally determined complex refractive index is then used to predict the radiative properties of the medium. The radiation transfer in the specimen that is calculated using the predicted radiative properties is seen to agree well with the corresponding experimental results.

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We study numerically one-dimensional interfaces by a Monte Carlo technique, where an interface is viewed as a loop embedded in one-, two- and three-dimensional Euclidean spaces. Since an actual interface has a surface tension, the action of the interface is defined on the basis of certain characteristic features possessed by a surface tension. The action contains an area energy term and a bending energy term with a dimensionless constant called rigidity. We find that the interfaces become smooth (crumpled) when the rigidity becomes large (small), and that there are no phase transitions of the first or second order. We can think of the absence of the phase transitions as indicating that there is no rapid mixing of the two materials separated by one-dimensional interfaces when the temperature of the system changes slowly.

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The effect of 0.34∼0.73% carbon content on phase transformation of carbon steel during quenching is examined experimentally. The temperature of Ar' phase transformation is a linear function of the cooling velocity at point A₁ (727°C) and is not influenced by the carbon content. The temperature of Ar" phase transformation is affected considerably by the carbon content. The latent heat of phase transformation is independent of carbon content. Experimental expressions of the temperature and the latent heat of phase transformation for hypo-eutectoid steel are presented. The calculated cooling curves using these expressions agree with the experimental results.

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The turbulent transition and turbulence characteristics of the plume above a line heat source in unstratified air are established by the statistical analysis of measured temperature. Spectra in the inertia-convective subrange and the inertia-diffusive subrange are expressed by S[s]=0.130f[Hz]^-5/3 and S[s]=0.275f[Hz]^-3.0, respectively. The laminar spectrum changes gradually to the turbulent spectrum in the transitional region. The plume spectrum enables us to exactly determine the flow state, i. e., laminar, transitional, or turbulent. The Grashof numbers for the beginning and the ending of the turbulent transition are Gr_s=2.0×10⁸ and Gr_e=2.0×10⁹, respectively. The frequency of the large-scale vortex in the turbulent region agrees well with the dominant frequency of the spectrum and the swaying frequency.

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The time-averaged temperature, the time record of temperature, the fluctuation intensity, and the autocorrelation coefficient of the plume are obtained experimentally. Stable stratification increases the plume temperature and the amplitude of temperature variation. The temperature time record has a regular form near the end of the laminar region. The fluctuation intensity has a minimum value in the turbulent or the transitional region. The autocorrelation is characterized in the laminar, transitional, turbulent, retransitional, and relaminar regions.

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Flow visualizations show that the buoyant plume above a line heat source in thermally stable stratified air has a vortex pair and a swaying motion. The stable stratification suppresses the plume height, increases the swaying amplitude, and generates a vortex pair near the plume front. The plume pattern changes into fumigation flow, the mushroom plume, the plume with the maximum amplitude of the swaying motion, and the plume with a glasseslike vortex pair, with increase of the heat rate. These four kinds of plume pattern do not occur in unstratified air and therefore characterize the plume in the stable stratification.

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The local details of the influence of horizontal vibration on heat transfer from a horizontal cylinder have been investigated numerically. In this work, a stable and efficient numerical scheme in the frequency domain was proposed and was applied to the above-mentioned problems. As a result the following facts have been revealed : (1) The local characteristics of heat transfer from a vibrating cylinder are different between the low-frequency vibration and the high-frequency one, although the convection fields, except for the vicinity of the cylinder surface, show similar features. This is related to the thickness of the inner steady vortex system caused by a vibrating cylinder. (2) For low-frequency vibration, the local heat transfer rate depends on the inner vortex flow because of the thick vortex system. (3) For high-frequency vibration, the inner vortex system becomes thin and acts like a solid film, hence the local heat transfer rate depends on the outer vortex flow.

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This study simulates cooling of a metal mold in 3-dimensions, compares it with experiments, and furthermore, attempts to establish a more precise simulation. We have analyzed heat generation at a gate and resinous flow in a cavity, and have considered the mold-temperature field in the filling process. The code enables both re-construction of 3-dimensional any practical molds with water jackets and its reform. Moving coordinates system is used to calculate the transient temperature-field in polymer-flow. As a result, we have been able to confirm agreements between the results of the experiment and the simulation. Therefore we have found that we are able to apply this program code to practical cooling process. There are still some problems in its further advancement, but this study is a foundation for cooling simulations.

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The effect of suction through holes bored in the cooling roll shell to promote heat transfer between the roll and strip is predicted analytically and verified experimentally. The effective contact area for contact heat transfer between strip and crowned roll is analysed numerically, and the width of contact area for the suction roll is compared with that of conventional cooling roll. The cooling roll with suction holes is made and tested in a production line. It showed higher cooling capacity and allowable wrapping angle than those of a conventional cooling roll.

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As NO_x produced in high temperature combustion consists of approximately 90% NO, it is very difficult to reduce NO concentration by chemical reaction because of very poor reaction rates. The findings show that (1) NO changes into N₂, CO₂ and CO at 300∼625°C by means of a chemical adsorption and dissociation process using pitchy tar carbon fiber felt as an adsorber and (2) this characteristic of NO reduction is influenced by the differences between isotropic and anisotropic (liquid crystal) molecular structures and baking procedures. This paper presents verification of the mechanism by surface investigation.

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A theoretical study has been performed to optimize the fin geometry of a horizontal low-finned condenser tube. Three classes of two-dimensional fins without circumferntial variation in the fin crosssection were considered. These included a parabolic fin, a rectangular fin with a round corner at the fin tip, and a newly proposed fin profile with a monotonically increasing radius of curvature near the fin tip and a constant thickness near the fin root. Curvilinear coordinates were used to describe the basic equations for the condensate film. Extensive numerical calculations with systematically changed values of geometric parameters were made of laminar film condensation on the three classes of fins with R11 and R123 as condensing fluids. Comparison of the numerical results revealed that the highest heat transfer performance was provided with the newly proposed fin. Numerical results were also presented that showed the effect of thermal conductivity of the fin material on the optimum fin geometry of the newly proposed fin.

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In direct injection diesel engines the intense swirling air motion in the cylinder is useful for a higher air fuel mixing rate. Therefore, we have investigated fuel spray motion in air flow with a uniform velocity distribution in order to explain the effect of the air swirl on the fuel spray motion in the cylinders of direct injection diesel engines, and concluded that the spray movement affected by the lateral air motion is controlled by the momentum of the fuel injection, the momentum of the air motion, the effective diameter of the fuel injection nozzle and factors of air entrainment. Then, the equation of the fuel spray motion locus in lateral air flow is obtained.

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In a previous paper, the "resonance factor" was proposed to quantitatively estimate the degree of combustion-driven oscillation potential in a furnace with a single gas burner. In this report, the technique is applied to a test furnace, where two multispud-type burners mounted oppositely are fired, and the following results are obtained. (1) The opposed-firing system oscillates stronger than the front-firing one. (2) The mode of oscillation in the opposed-firing system is equivalent to the first mode observed in a closed-ended tube, but slightly different from the mode of a front-firing system. (3) The shorter the furnace depth, the more stable the combustion state.

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A combination of an optical fiber thermometer (OFT) and a beveled-edge-type light pipe sensor was used to measure flame temperature and soot concentration accurately in a DI diesel engine combustion chamber through a simple and easy procedure applying an infrared two-color method. The influence of sensor contamination due to combustion on the OFT output was examined and the appropriate correction method was applied for compensation of the decreased OFT output. The changes in combustion temperature and soot concentration were measured and compared with the exhaust emission levels by varying parameters such as engine speed and torque, fuel injection timing and suction air temperature. As a result, it was shown that this measuring technique is useful and effective in evaluating the combustion process in a diesel engine.

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The authors have proposed new techniques for measuring combustion behavior locally in a DI diesel engine combustion chamber by means of an optical fiber thermometer; one technique is to use two types of light pipe sensor with different measuring spaces and the other is to vary the measuring space only by rotating the axis of the beveled-edge-type light pipe sensor. Results obtained in this experiment are as follows: (1) Cyclic variation of combustion differs significantly from space to space in the combustion chamber. (2) Flame temperature varies a little locally, but the soot concentration varies considerably in the combustion chamber especially at the stage of initial combustion. (3) The soot formation process begins at a crank angle about two degrees after ignition.

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Fuel consumption of the engine becomes sufficiently economical when it runs under operating conditions of low speed and high torque rather than of high speed and low torque. However, it is difficult for automobiles to run under such economical conditions because acceleration is frequently required. Therefore, if an automobile engine is operated by consolidated control with continuously variable transmission (CVT), the minimum fuel consumption will be achieved, satisfying the driver's demand for a particular vehicle speed. The advantage of this consolidated control for fuel economy depends on several factors, such as specifications of the automobile, the performance of controllers, the driving mode of the automobile and the performance of the control actuators. In this report, the required CVT's operating speed which involves the performance of the actuators was investigated by simulation studies as well as theoretical analysis.

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This experimental visualization study focuses on the air-fuel mixture formation inside LDISC (low-pressure direct injection statified charge) rotary engines with the side-port intake system. Nonlubrication rotary engines newly designed with transparent side housings have made optical visualization methods applicable. The flow fields and the fuel vapor distributions are visualized with the laser light sheet method and the Schlieren method, respectively. Motion pictures show that the vortices which give major features to the flow fields play a key role in the air-fuel mixture formation process. Given the experimental data, this paper concludes that what are significant to the air-fuel mixing process are intake pressure conditions and rotor geometries.

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A numerical method has been investigated for predicting the sound characteristics and the pressure losses of intake silencers in internal combustion engines. Firstly, the gas exchange process in intake and exhaust systems has been calculated by a one-dimensional characteristic method. Using these calculated results as the boundary conditions, the two-dimensional calculation of unsteady gas flow in the silencers has been carried out by means of a finite difference method. The results show that the behavior of the pressure wave propagation and the gas motion in largely fluctuating flow fields is well simulated with little false diffusion by applying a CIP (Cubic Interpolated Pseudo-Particle) method. Consequently, the present numerical method could be useful to predict both the sound characteristics and the pressure losses of real silencers by developing the method into the three-dimensional analysis.

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